Parallel-Axis Friction Brake for Stable Drag Torque Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing drag brake mechanisms in automotive closure systems suffer from stick-slip issues, wear, torque degradation, and temperature dependence, while also being costly and space-consuming, limiting their effectiveness and user experience.
Innovation Solution
The use of a parallel axis friction brake with a friction assembly that includes a shaft parallel to the output screw, providing higher pressure and minimizing stick-slip through a smaller diameter design, which enhances torque control and reduces travel per revolution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If a friction brake mechanism is used to create drag, then drag torque is provided, but stick-slip issues occur causing erratic user feel
Solution Approach 1:
The brake mechanism is segmented into multiple friction clips (typically three) distributed around the circumference of the output screw. Each clip independently contacts the screw surface, distributing the friction force across multiple points. This segmentation prevents concentrated stick-slip events and provides smoother, more consistent drag torque delivery throughout the rotation cycle.
Solution Approach 2:
The friction clips are positioned at specific angular locations around the output screw circumference, creating localized friction contact zones. This local quality approach ensures that at any given moment, multiple clips are in contact with the screw at different positions, maintaining continuous and stable friction engagement without the erratic stick-slip behavior associated with single-point contact brakes.
2Force
If conventional friction brake designs are used, then drag is provided, but wear and torque degradation occur over the actuator's life
Solution Approach 1:
By distributing friction contact across multiple clips rather than a single friction surface, the wear is divided and shared among several contact points. This segmentation of the friction interface reduces the wear rate at each individual clip-screw contact zone, thereby extending the overall service life and maintaining torque consistency throughout the actuator's operational lifespan.
Solution Approach 2:
The friction clips are designed to naturally conform to the output screw surface through elastic deformation, ensuring consistent contact pressure and uniform wear distribution. This self-adjusting mechanism maintains optimal friction engagement without requiring external adjustment or intervention, preserving torque consistency over the actuator's life.
3Force
If friction brake mechanisms are used, then drag torque is created, but torque varies with temperature changes
Solution Approach 1:
The multiple-clip configuration segments the thermal response of the friction system. As temperature changes occur during actuator operation, the distributed clips experience thermal effects at different locations and times, averaging out temperature-induced torque variations. This segmentation provides inherent thermal compensation, maintaining more stable drag torque across the operating temperature range.
4Area of stationary object
If space constraints are considered for automotive closure systems, then compact design is needed, but conventional brakes consume excessive space
Solution Approach 1:
The brake mechanism is merged with the existing actuator structure by mounting the friction clips directly on the output screw and housing components that are already part of the actuator assembly. This integration eliminates the need for separate brake housings and mounting structures, achieving a compact design that fits within the constrained space of automotive closure systems while maintaining manufacturing simplicity through the use of standard fastening and mounting techniques.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The parallel axis friction brake design significantly improves stick-slip performance and temperature stability, maintaining precise drag torque control over the actuator's life, while being compact and cost-effective.
Implementation Method 1
a friction assembly that includes a shaft parallel to the output screw
Data Source
AI summary
One aspect is an actuator system having a rotatable drive shaft and a parallel axis friction brake engaged with the drive shaft and configured to provide a drag force on the rotatable drive shaft. The parallel axis friction brake further includes a brake housing and a friction assembly that has at least one parallel axis shaft and at least one clip pressed over the at least one parallel shaft in an interference fit. The friction assembly is engaged with the drive shaft and coupled to the brake housing, at least a portion of the friction assembly rotating with the rotatable drive shaft to create the drag force.